AimsThis study was conducted to examine the effect of telephone counseling based on the Information, Motivation, Behavioral Skills (IMB) Model on HbA1c and self-management in patients with type 2 diabetes mellitus (T2DM). MethodsThis study was conducted between January 2019 and September 2019 with a total of 63 (31 interventions, 32 controls) T2DM patients. The intervention group was followed-up for a total of 12 weeks, after 45−60 min of patient training based on IMB, a weekly reminder message and a phone call every two weeks. No intervention was made to the control group. Data were collected at the beginning of the study and at the end of the 12th week. The data were obtained using a Patient Information Form, the Type 2 Diabetes Self-Efficacy Scale, the Diabetes Self-Management Questionnaire (DSMQ), the Perceived Diabetes Self Management Scale (PDSMS) and glycemic control (HbA1c). ResultsParticipants were on average 54 years old and the majority were female (58.1%). According to the results of the covariance analysis (ANCOVA), there was a statistically significant difference between the pre-post-test HbA1c (F:13.589; p < 0.001), weight (F:32.176; p < 0.001) and systolic blood pressure (F:7.109; p = 0.01). However, there was no significant difference in diastolic blood pressure between the intervention and control groups (F:2.686; p = 0.106). Also, after three months of follow-up, self-efficacy (F:26.632; p < 0.001), self-management (F:44.487; p < 0.001) and self-management perceptions (F:71.132; p < 0.001) were significantly higher in the intervention group. ConclusionThe researchers concluded that telephone counseling based on the IMB model could be a suitable method to improve glycemic control and self-care behaviors in patients with type 2 diabetes.